Bone stabilizing implants and methods of placement across si joints

ABSTRACT

Threaded sacro-iliac joint stabilization (e.g., fusion, fixation) implants and methods of implantation and manufacture. Some implants include a threaded distal region, an optionally threaded central region, and an optionally threaded proximal region. The distal, central, and proximal regions have lengths such that when the implant is laterally implanted across a SI joint, the distal region can be positioned in a sacrum, the central region can be positioned across an SI-joint, and the proximal region can be positioned in an ilium.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/US2020/062275, filed Nov. 25, 2020, which claims thebenefit of priority to U.S. Provisional Application No. 62/941,507,filed Nov. 27, 2019, the entire disclosure of which are incorporated byreference herein in its entirety for all purposes.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BACKGROUND

The SI-Joint functions in the transmission of forces from the spine tothe lower extremities, and vice-versa. The SI-Joint has been describedas a pain generator for up to 22% of lower back pain. To relieve paingenerated from the SI Joint, SI Joint fusion is typically indicated assurgical treatment, e.g., for degenerative sacroiliitis, inflammatorysacroiliitis, iatrogenic instability of the sacroiliac joint, osteitiscondensans ilii, or traumatic fracture dislocation of the pelvis. Thereis a continued need for improved threaded SI Joint fixation and fusionimplants.

SUMMARY OF THE DISCLOSURE

One aspect of the disclosure is a threaded bone implant (“implant”). Theimplant may include an elongate body having a distal end and a proximalend. The elongate body may include a threaded multi-lead distal region,a threaded single-lead central region disposed proximally of themulti-lead distal region, and a threaded multi-lead proximal regiondisposed proximally of the single-lead central region. The elongate bodyhas a length, and the threaded multi-lead distal region, the threadedsingle-lead central region, and the threaded multi-lead proximal regionmay each have individual lengths such that when the implant is laterallyimplanted, the multi-threaded distal region can be positioned in asacrum, the single-lead central region can be positioned across aSI-joint, and the multi-lead proximal region can be positioned in anilium.

In this aspect, the threaded multi-lead distal region may be betteradapted to anchor into dense sacral bone than the threaded single leadcentral region.

In this aspect, the threaded multi-lead proximal region may be betterconfigured to anchor into dense iliac bone than the threaded single leadcentral region.

In this aspect, one or both of the multi-lead distal region and themulti-lead proximal region may be a dual-lead threaded region.

In this aspect, the multi-lead distal region, single-lead centralregion, and multi-lead proximal region may all comprise an inner shankfrom which the respective thread radially extends and a porous networkof interconnected struts disposed about the inner shank and in betweenthreads. A proximal region or portion of the threaded single-leadcentral region may be free of a porous network of interconnected struts,and a threaded single-lead central region may have a major diameter from9 mm to 11 mm (the outer diameter of the thread).

In this aspect, a threaded multi-lead distal region may be a dual-leaddistal region comprising a pattern of high and low threads.

In this aspect, a threaded multi-lead proximal region may be a dual-leaddistal region comprising a pattern of high and low threads.

In this aspect, a first thread may be continuous and extend from thedistal region, through the central region, and into the proximal region.A continuous thread in this regard may be interrupted by a plurality offenestrations and/or flutes extending through the elongate body.

In this aspect, the elongate body may further have a plurality ofhelical flutes formed therein, each of the plurality of flutes extendingin the multi-lead distal region, the single-lead central region, andoptionally in the multi-lead proximal region. A plurality of helicalflutes may consist of three helical flutes in the elongate implant body.Each of a plurality of flutes may have a plurality of fenestrationsaligned with the respective flute, the fenestrations spaced from eachother along a length of the flute and extending into an elongate bodycentral lumen or area. Each of a plurality of fenestrations may have aradially inward tapered configuration. At least one of a plurality offenestrations may be disposed in the distal region, at least one of theplurality of fenestrations may be disposed in the central region, and atleast one of the plurality of fenestrations may be disposed in theproximal region. In some embodiments the proximal region is free offenestrations.

In this aspect, a first fenestration in the distal region may be largerthan a second fenestration in the central region, and optionally each ofa plurality of distal fenestrations may be larger than each of aplurality of central fenestrations.

In this aspect, the elongate body may further comprise a plurality offenestrations therethrough. A first fenestration in the distal regionmay be larger than a second fenestration in the central region. In someembodiments, each of a plurality of distal fenestrations may be largerthan each of a plurality of central fenestrations.

In this aspect, a proximal region of the elongate body may be tapered,with a proximal end having a larger radial dimension than a distal endof the proximal region.

In this aspect, at least one of the threads may have an inverse filletthat is curved.

In this aspect, a proximal end of the elongate body may be counter-sunk.

In this aspect, the length of the distal region may be from 10 mm to 22mm.

In this aspect, the length of the central region may be from 8 mm to 56mm.

In this aspect, the length of the proximal region may be from 6 mm to 10mm.

This aspect may further include any suitable implant feature describedherein.

One aspect of this disclosure is a threaded bone stabilization implantadapted for a lateral delivery and sized for placement across asacro-iliac (“SI”) joint. The implant includes an elongate body having adistal end and a proximal end. The elongate body may include a threadeddistal region, a threaded central region disposed proximally of thedistal region, and a proximal region disposed proximally of the centralregion. The elongate body may further include a plurality of helicalflutes, each of the plurality of helical flutes having formedtherethrough a plurality of fenestrations extending into a centrallumen. The body may have a length, and the threaded distal region, thethreaded central region, and the proximal region may each haveindividual lengths such that when the implant is laterally implanted,the threaded distal region can be positioned in a sacrum, the threadedcentral region can be positioned across an SI-joint, and the proximalregion can be positioned in an ilium.

This aspect may additionally comprise any other suitable threadedimplant feature described herein.

One aspect of this disclosure is a threaded bone implant. The implantincludes an elongate body extending from a distal end to a proximal end.The elongate body may include one or more helical threads, each of theone or more helical threads extending axially along at least a portionof the elongate body. The elongate body may include an inner shank orinner member from which the one or more helical threads radially extend.The elongate body may also include a porous network of interconnectedstruts disposed about the inner shank (or inner member) and about alongitudinal axis of the elongate bone implant body. A porous network ofinterconnected struts may be disposed between the one or more helicalthreads along at least a section of the elongate body, and optionallydisposed in each of a distal region, a central region, and a proximalregion of the implant. In some examples a porous network ofinterconnected struts has a continuous helical configuration through adistal region, a central region, and into a proximal region. Continuousin this context and as used herein includes discontinuities in theporous network due to one or more flutes and/or one or morefenestrations. A porous network of interconnected struts may have anouter dimension that is less than a major diameter of the one or morehelical threads.

This aspect may include any other suitable threaded implant featuredescribed herein.

One aspect of this disclosure is a method of manufacturing a threadedbone implant. The method may include printing a threaded bone implantfrom a distal end to a proximal end (although printing from a proximalend (head) to a distal end (tip) may be used in some alternativeembodiments). Printing the implant may include printing an inner shank,printing one or more helical threads extending radially from the innershank, each of the one or more helical threads extending along at leasta portion of the threaded bone implant. The method may include printinga porous network of interconnected struts about the inner shank, about along axis of the elongate bone implant body, and between at least asection of the one or more helical threads. The porous network ofinterconnected struts generally has an outer dimension less than a majordiameter of the one or more helical threads.

This aspect may include any other suitable method step herein, and maybe a computer executable method stored in a memory and adapted to beexecuted by a processor or processing component, concepts of which areknown (e.g., one or more pieces of software, an algorithm, etc.)

One aspect of the disclosure is a method of 3D printing a threaded boneimplant. The method may include printing a threaded bone implant from adistal end to a proximal end. Printing the implant may include printinga sacrificial distal tip, printing a threaded bone implant above thesacrificial distal tip, and subsequent in time to printing the threadedbone implant, removing the sacrificial tip and forming a distal end onthe threaded bone implant.

This aspect may include any other suitable method described herein.

One aspect of this disclosure is a 3D printed threaded bone implant. Theimplant may include a 3D printed implant body having a distal end and aproximal end. The implant body may have one or more threads thereonextending radially outward from an inner shank. At least one thread mayform an angle greater than 45 degrees relative to a long axis of theimplant body.

This aspect may include any other suitable feature related to threadedbone implants herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an exemplary threaded implant.

FIG. 2 is a side view of an exemplary threaded implant.

FIG. 3 is a side view of an exemplary threaded implant.

FIG. 4 is a side view of an exemplary threaded implant.

FIG. 5 is a side view of an exemplary lag threaded implant and washer.

FIG. 6 is a side view of an exemplary lag threaded implant and washer.

FIG. 7 is a perspective view of an exemplary threaded implant.

FIG. 8 is a side view of an exemplary threaded implant including afluted region, a fenestration, and a porous network of interconnectedstruts.

FIG. 9 is a side view of an exemplary threaded implant including aporous network of interconnected struts between threads.

FIG. 10 is a side view of an exemplary threaded implant includingflutes, as well as a porous network of interconnected struts disposedbetween threads.

FIG. 11 illustrates an exemplary thread angle alpha referenced herein.

FIGS. 12A and 12B illustrates an exemplary orientation for manufacturingthreaded implants herein.

DETAILED DESCRIPTION

The disclosure relates generally to threaded bone stabilizing implants,which may be used for fixation and/or fusion, for example. The bonestabilizing implants described herein are generally sized and configuredto be delivered in a lateral delivery pathway and implanted such that adistal region of the implant is implanted in a sacrum, an intermediateregion is implanted in or across a sacro-iliac (“SI”) joint, and aproximal region is implanted in an ilium. The bone implants hereininclude one or more threads along at least a portion of the implant,which allows the implants to be rotated into and anchored into boneduring implantation. When an implant herein is referred to as a threadedimplant, it refers to an implant having one or more threads, any one ofwhich may extend along at least a portion of a length of the implant.

The threaded bone implants herein generally include different regions orportions along their lengths that are sized and/or configured to providefunctionality based at least partially on the anatomical region in whichthey implanted. For example, implants herein may have distal regionsthat are sized (e.g., length and/or width) and configured (e.g.,threaded) such that the distal region is adapted with functionality toanchor into relatively more dense cancellous sacral bone. Thefunctionality may be compared relative to other regions of the implantthat are not so sized and/or configured, or to other types of implantsthat are not so sized and/or configured in the manner(s) describedherein.

The disclosure herein may be related to disclosure from U.S.Publication. Nos. 2018/0228621, 2013/0296953 and 20150105828, the entiredisclosures of which are incorporated by reference herein for allpurposes.

FIG. 1 illustrates an exemplary bone stabilization implant 100 thatincludes an elongate body as shown, the elongate body extending fromdistal end 102 to proximal end 104. The elongate body includes distalanchor region 120, intermediate or central region 140, and proximalregion 160. In this embodiment, distal region 120 includes a threadedregion that is multi-lead, and in this particular example is dual-lead,with threads 122 a and 122 b shown in FIG. 1.

Distal region 120 also includes a porous network of interconnectedstruts 124 in between the threads, one region of which is labeled inFIG. 1. A porous network of interconnected struts may be referred toherein as a porous lattice. FIG. 1 illustrates an example of a porousnetwork of interconnected struts that may be considered to have ageneral helical configuration that extends between helical threads ofthe threaded region, as shown. The helical configuration of the porouslattice may be interrupted by one or more fenestrations and/or fluteswhere no lattice is present (such as shown in FIG. 1), but the porouslattice may still be considered to have a general helical configurationin these examples.

Distal region 120 is multi-lead (dual-lead in this example), theconfiguration of which adapts distal region 120 to more securely anchorinto dense cancellous sacral bone.

The porous lattices herein may comprise an outer porous network ofinterconnected struts, an example of which is shown in FIG. 1, and whichare described in more detail below. Any of the individual struts hereinmay also be referred to as a beam. Generally, the porous regions inbetween the threads preferably have a smooth outer profile to facilitaterotational insertion and proper anchoring. Alternatively stated, it isgenerally desirable for the porous regions in between threads to avoidhaving a significantly rough outer surface with exposed strut ends,which may deleteriously damage the adjacent bone and result in lessstable anchoring. The porous network may have an irregular configurationof struts, or it may have a regular pattern of struts, or a combinationthereof. It is therefore understood that the term lattice as used hereindoes not require a regular or repeating pattern of struts. Additionalexemplary features of porous networks of interconnected struts aredescribed below.

The implant 100 also includes central or intermediate region 140, whichis sized and configured (including relative to other implants regions)to be positioned across a SI joint when the implant 100 is deliveredlaterally across the SI joint. Central region 140 includes a fewer-leadthreaded region than distal region 120 and proximal region 160, and inthis embodiment is single-lead. In this embodiment thread 142 in centralregion 140 is considered to continue into distal region 120 as thread122 b, as shown, but in alternative embodiments the central regionthread may be considered part of a different thread that does notcontinue or extend into distal region 120. Thread 122 b is consideredcontinuous with thread 142 from distal region 120 into central region140, even though the thread is interrupted one or more times byfenestrations and fluted regions, which are described in more detailbelow.

Central region 140 includes a porous network of interconnected struts144 (which may be referred to here as a lattice), only one region ofwhich is labeled in FIG. 1. Lattice 144, like lattice 124, is disposedbetween threads in central region 140. The porous lattice 144 may beconsidered continuous with porous lattice 124 in that they togetherapproximate a generally helical configuration extending from distalregion 120 into central region 140, which again is interrupted by one ormore fenestrations and fluted region as shown.

The exemplary single-lead design in central region 140 provides forrelatively greater axial spacing between threads, compared to, forexample, distal region 120. This relatively greater axially spacingcreates a greater porous lattice 144 surface area, which is betteradapted and configured to facilitate ingrowth and/or ongrowth whencentral region 140 is implanted across the SI joint. Distal region 120and central region 140 are examples of regions in which the centralregion has a relatively greater spacing between threads, which providesfor a greater porous surface area between threads.

The elongate body also includes proximal region 160, which includes athreaded region with a greater lead than central region 140. In thisexample, proximal region 160 includes a threaded region that isdual-lead, as shown. Thread 162 a in proximal region 160 is continuouswith thread 142 in central region 140, although in alternativeembodiments they may not be continuous. It is again understood that thephrase continuous in this context includes one or more interruptionswith fluted region and/or fenestrations, as shown in FIG. 1. Themulti-lead threaded region in proximal region 160 facilitates stronganchoring in dense iliac bone when implant 100 is implanted laterallyacross a SI joint.

As mentioned above, implants herein may have a distal region, a centralregion and a proximal region that are each configured and sized toprovide one or more functions based on the anatomical region in whichthey are positioned after the implant is fully implanted. In someembodiments, any of the distal regions herein (e.g., distal region 120in FIG. 1) may have a length from 10 mm to 22 mm, for example. This mayensure that the multi-lead region is anchored into dense sacral bonenear the mid sacrum. In some embodiments, any of the central regionsherein (e.g., central region 140) may have a length from 8 mm to 56 mm.This may ensure that the central region is positioned across the SIjoint, with the relatively larger porous surface area extending acrossthe joint to facilitate one or more of ingrowth and/or ongrowth areas.In some embodiments, any of the proximal regions herein (e.g., proximalregion 160 in FIG. 1) may have lengths from 6 mm to 10 mm, which canensure that the multi-lead threaded proximal region is anchored intodense iliac bone. The proximal regions herein with respect to theirlengths are not considered to include a proximal end of the elongatebody that is free of threads, such as where reference number 104 ispointing in FIG. 1.

Implant body 100 also includes an inner shank or inner member from whichthe one or more threads and one or more porous lattice regions radiallyextend. The inner shank may be considered the same or similar to a shankof a screw or other threaded body. The inner shanks herein need not beconsidered to be continuous structures, and may include one or morebreaks or discontinuities therein, such as one or more fenestrationsextending therethrough. The inner shank or inner members herein in thiscontext may be considered to include inner surfaces from which one ormore threads and one more porous lattice structures extend radiallytherefrom.

The distal region 120 is tapered towards its distal end, as shown inFIG. 1, a feature of which may be incorporated into any of the implantsherein. Distal end 102 in this example also includes sharpened distalend elements, which may be incorporated into any of the implants herein.

FIG. 2 illustrates an exemplary threaded bone implant 200. Implant 200may have one or more features of implant 100 in FIG. 1, includingfeatures that may be similarly labeled (e.g., 120 and 220). Onedifference between implant 100 and implant 200 is that implant 200includes a central region, a proximal portion 246 of which is void orfree of a porous network of interconnected struts. Proximal portion 246,which may be considered a solid portion, is disposed at the SI jointwhen the implant is fully implanted. The proximal portion 246 of thecentral single threaded region 240 includes inner member or inner shank248 and a thread radially extending therefrom. In some embodiments,implant 200 may be the same as implant 100 in all other ways. As shownin FIG. 2, shank 248 in proximal portion 246 has the same orsubstantially the same radial dimension (e.g., diameter) as the porousnetwork of interconnected struts 244 in the distal portion of thecentral region 240. An exemplary advantage of the proximal portion 246without the lattice, and the larger diameter shank in proximal portion246, is that proximal region 246 may be stronger and more fatigueresistant in the region of the larger diameter shank. This may beimportant on some bone implants with certain dimensions where includinga lattice structure along its entire length, including a region acrossthe SI joint, may reduce fatigue strength to an extent that isundesired. For example, in some embodiments, implant 200 may have amajor diameter from 9 mm to 11 mm (outer diameter of the thread), suchas 10 mm.

As shown in FIG. 2, inner shank 248 has step-up in region 210 in centralregion 240, where the diameter of the shank increases at the step-upfrom the distal portion of central region 240 to proximal portion 246 ofcentral region 240. The step-up in shank diameter increases the fatiguestrength in the proximal portion 246, which is generally positionedacross the joint.

FIGS. 3-6 illustrate exemplary lag threaded implants 300-600,respectively, in which the central regions and proximal regions are notthreaded, as shown. The lag implants include a proximal washer, asshown, methods of use of which are generally known for lag implants. Insome applications, the threaded lag implants herein may be used forfracture and repair, for example.

FIG. 3 illustrates an exemplary threaded lag implant 300 that includes adistal threaded region 320, a central non-threaded region 340 spaced tobe disposed across a SI joint, and a proximal non-threaded region 360.Distal region 340 is multi-lead, and in this embodiment in dual-lead.Implant 300 includes a plurality of helical flutes or fluted region 370(e.g., 370 a, 370 b and 370 c, as shown). Implant 300 further includes aplurality of fenestrations 380, which may be similar or the same as anyof the fenestrations herein. For example, and as shown, each of thehelical flutes 370 is aligned with a plurality of fenestrations 380.Fenestrations in the distal region 320 may be larger than fenestrationsin the central and/or proximal regions 340 and 360 respectively, such asfor the reasons set forth herein.

As shown in FIG. 3, implant 300 includes porous lattice or network ofinterconnected struts 324, additional exemplary details of which aredescribed herein. Porous lattice 324 may also be considered to have ahelical configuration, disposed between both threads 322 and the flutes,as shown. In this example, the porous lattice extends in the distalregion 320, the central region 340, and into the proximal region 360.Any of the description herein related to a porous network ofinterconnected struts may be incorporated into lattice 324. Washer 390is also shown, and is configured to be disposed about the proximal endof implant 300 and allows for a range of motion between implant 300 andwasher 390.

FIG. 4 illustrates implant 400 and illustrates features similar or thesame as implant 200 in FIG. 2, in particular a proximal portion ofcentral region 440 that is free of a porous lattice. The relevantdescription of FIG. 2 with respect to a section free of a porous latticeis incorporated by reference into the description of implant 400 in FIG.4 for all purposes. An exemplary advantage of the proximal portion ofthe central region 440 without the lattice as shown, and the largerdiameter shank in the proximal portion of central region 440, is thatthe proximal region may be stronger and more fatigue resistant in theregion of the larger diameter shank, for the same reasons set forthherein with respect to FIG. 2.

FIG. 5 illustrates implant 400 from FIG. 4, and also illustrates anexemplary angle of rotation and washer 490, with implant 400′ shown toillustrate the exemplary angle of rotation.

FIG. 6 illustrates implant 600 that may be similar or the same asimplant 300 shown in FIG. 3. FIG. 6 illustrates an exemplary angle ofrotation and 690. Any suitable description herein related to implant 300is incorporated by reference into the disclosure of FIG. 6.

Threaded bone implants herein may include one or more flutes, or flutedregions, examples of which are shown in FIGS. 1-6. FIG. 7 illustratesexemplary threaded bone implant 700, which may include any othersuitable feature of any other threaded bone implant described herein.Implant 700 has an elongate body that includes a plurality of helicalflutes or fluted regions 770 a, 770 b, 770 c, extending along at least aportion of the length of the elongate body. Similarly, FIG. 2 showsimplant 200 including a plurality of helical flutes 270 a, 270 b and 270c formed therein. Threaded bone implants herein may include three flutes(as shown in the examples of FIGS. 2 and 7), although implants hereinmay be modified to include more or fewer than three flutes.

Implant 700 also includes fenestrations 780, only two of which arelabeled in FIG. 7. Implant 700 is another example of an implant bodythat includes flutes 770 that are each aligned with a separate pluralityof fenestrations 780 formed through the elongate body. Each flutedregion in this example includes a separate plurality or set offenestrations aligned with the respective fluted region, as is shown inFIG. 7.

FIGS. 2 and 7 show exemplary implants that include a plurality ofhelical flutes, each of which extends from the distal region and intoand through the central region, and which may optionally extend in theproximal regions. As shown in FIG. 2, the plurality of helical flutesmay extend to a minimal extent into the proximal multi-lead region 260,but the flutes may optionally not extend all the way through proximalregions herein.

As is shown in FIGS. 2 and 7 (but shown in other embodiments herein),the flutes or fluted regions (as well as one or more of thefenestrations) of the implant create an interruption in the one or morethreads that extend around the elongate body.

The threaded implants herein may include one or more fenestrations, orrelatively larger apertures, extending therethrough. FIG. 2 illustratesa plurality of fenestrations 280 (only two of which are labeled). FIGS.2 and 7 are examples of threaded implants in which at least one(optionally all) of the fenestrations is aligned, or overlaps with, afluted region of the implant. FIGS. 2 and 7 each illustrate a pluralityof fluted regions of the respective threaded implant, each of which isaligned or overlapped with a plurality of fenestrations. Thefenestrations aligned with or overlapping each of the fluted regions areaxially spaced apart along the fluted region, and together thefenestrations are disposed in a helical configuration, as shown moreclearly in FIG. 7. In FIGS. 2 and 7, for example, there are three setsof helically-oriented fenestrations, each set including a plurality offenestrations.

In any of the embodiments herein, any or all of the fenestrations in theimplant may have a tapered configuration in the radial direction. FIG. 8illustrates a single fenestration 880 in a threaded implant elongatebody having a tapered configuration between a larger radially outerfenestration opening 881 and a smaller radially inner fenestrationopening 882, wherein the difference in opening sizes defines the taperedconfiguration. This type of taper is referred to herein as a radiallyinward taper. Any or all of the fenestrations in the threaded implantmay be tapered in this manner. Fenestration 880 is also an example of afenestration aligned with a fluted region, as shown. FIG. 8 is also anexample of a continuous thread, as shown, that is interrupted by afluted region and fenestration 880.

Any of the implants herein may have a plurality of fenestrations, butnot all of the implant fenestrations may have the same size orconfiguration as one or more other fenestrations in the implant. Forexample, in some embodiments, a distal region of the implant (e.g.,distal region 220 in FIG. 2) may not need to have as much fatiguestrength as a more proximally disposed region, such as central region240, or a proximal portion 246 of the central region, which may beimplanted across a SI joint. Any of the implants herein may thus havedistal regions with one or more fenestrations therein that are largerthan one or more fenestrations in at least a portion of the centralregion that is disposed across the SI joint. The threaded implantcentral regions may have smaller fenestration so that the implant hasmore structural material in the region that is disposed across the SIjoint. The distal region, which may not need the same fatigue strength,can have more openings, such as in the form of larger fenestrations,without negatively impacting strength of the implant.

Additionally, any of the implants herein may include fenestrations inthe distal region that have less pronounced tapers in which there isless of a difference in size or circumferential area between theradially inner opening and the radially outer opening (i.e., a steepertransition between the inner opening and the outer opening). Compared toone or more central region fenestrations, distal region fenestrationsmay have radially inner openings that are relatively larger thanradially inner openings in the central region of the implant.

As described herein, any of the implants herein may include porousregions disposed radially outward from an inner member or shank, whereinthe porous regions extend along at least a portion of the threadedimplant, including in regions in between the one or more threads. Forexample, FIG. 1 shows implant 100 that includes porous network ofinterconnected struts (e.g., 124) in between threads and extending alongsubstantially all of the elongate body. FIG. 2 shows an example of animplant 200 that includes porous regions (e.g., 224) in between threadsand extending along at least a distal region of an implant, and in aproximal region of the implant.

Any of the porous network of interconnected struts herein (e.g., lattice144 in FIG. 1, porous lattice 244 in FIG. 2) may be a porous network ofinterconnected struts disposed about the inner shank, an example ofwhich is shown in FIG. 9. With threaded implants such as those describedherein, it may be desirable to have the porous network of interconnectedstruts that are between the threads to rotationally approximate a smoothshank and thereby facilitate a smooth rotational entry into the bone.This can create a minimal amount of resistance and bony damage as thethreaded implant is rotated through bone, helping securely anchor thethreaded implant into bone. This may be contrasted with porous regionthat include struts with many free ends that extend radially outward andare not interconnected with other struts as a network. The porousregions herein may be configured as a porous network of interconnectedstruts that are disposed about an inner shank (e.g., 948), an exemplaryhighlighted region of which is shown in FIG. 9.

FIG. 9 illustrates a portion of an exemplary implant 900 includingthread 922, in between which the implant includes a porous network ofinterconnected struts 944. Network of interconnected struts 944 includesa plurality of interconnected struts 950 (e.g., 950 a, 950 b, 950 c),only some of which are labeled in FIG. 9 for clarity. The struts 950 areinterconnected at connections or nodal locations 951, and only two ofwhich are labeled for clarity—951 a and 951 b. The connections or nodallocations herein may be the connection of two, three, four, or moreindividual struts or beams of the porous network of interconnectedstruts. As set forth above, the porous network of interconnected strutspreferably creates a smooth outer surface and may approximate acylindrical shank (even though the network defines a plurality of poresbetween the struts), which facilitate a relatively smooth rotation ofthe implant through bone.

The porous network of interconnected struts has an outer dimension lessthan a major diameter (diameter of thread(s)) of the at least onehelical thread, which is shown in at least FIGS. 8 and 9.

The porous networks of interconnected struts herein may be defined in avariety of ways. For example, the porous network of interconnectedstruts may be considered to be substantially concentric about a longaxis of the elongate body in at least a portion of the porous network ofinterconnected struts, which is partially shown in the perspective viewof FIG. 7. Additionally, the interconnected struts in the porousnetworks of interconnected struts herein may be considered to have thesame radially outermost dimension and concentric about an elongate bodylong axis. The porous networks of interconnected struts herein may beconsidered to define a generally circular shape in an end view of theelongate body, which is partially shown in FIG. 7. Additionally, theinterconnected struts in the porous networks of interconnected strutsherein may be considered to approximate an outer cylindrical profile,even though there are pores defined by the struts, and even thoughthreads may interrupt sections of the outer cylindrical profile.Additionally, the porous network of interconnected struts may beconsidered to define a generally cylindrical outer profile, even thoughthere are pores defined by the struts, and even though threads mayinterrupt sections of the generally cylindrical profile. Additionally,the porous networks of interconnected struts may be considered to definea substantially smooth outer surface, even though there are poresdefined by the struts. Additionally, any of the porous networks ofinterconnected struts herein may be considered to include radially outerstruts, which are substantially free of strut free ends extendingradially outward.

As shown in FIG. 9, the porous lattice may further include a pluralityof generally radially extending struts 952 that extend radially outwardfrom the inner shank or inner member 948 and connect to the porousnetwork of interconnected struts. The plurality of radially extendingstruts 952 generally couple the inner shank 948 to the outer porousnetwork of interconnected struts. Radially extending struts as describedin this context (e.g., strut 952) are not necessarily orthogonal, asthey may have some radial dimension in addition to some axial dimension.

In any of the embodiments herein, the porous network of interconnectedstruts includes struts or beams, any of which may have a diameter from0.175 mm to 0.300 mm.

In any of the embodiments herein, the porous network of interconnectedstruts may include point spacings from 0.375 mm to 0.525 mm.

In some embodiments herein, such as is shown in FIG. 1, the porousnetworks of interconnected struts may have or define a general helicalconfiguration extending along the elongate body between the at least onehelical thread. Helically extending porous networks herein may haveinterruptions formed therein and are still considered to have helicalconfigurations.

Any of the porous networks of interconnected struts herein may includeone or more end regions including strut free ends (e.g., 883 in FIG. 8),wherein the strut free ends are coupled or extending from a flutedregion of the elongate bone implant body, particularly in embodiments inwhich the threaded implanted is 3D printed. A strut free end in thiscontext refers to a strut end that is not directly connected to anotherstrut, and may be directly connected to another portion of the implantsuch as an inner shank, a thread or a flute, for example.

Any the threaded implants herein may be 3D printed, using one or moregenerally known methods or techniques. FIG. 11 illustrates a portion ofan exemplary implant 1100, which may include any of the features of anyof the threaded bone implants herein. Relative distal and proximaldirections are labeled. Thread 1122 shown in FIG. 11 may be the same orsubstantially the same as any of the threads shown in the examples ofFIGS. 1-10. When threaded bone implants herein, including the threadsdescribed herein, are 3D printed with the proximal or head side down,the threads are printed in the orientation shown in FIG. 11. When anglealpha as shown is large enough, the threads may tend to droop proximally(towards the head) during a 3D printing process. For example, in someembodiments, alpha may be greater than 45 degrees, such as from 45degrees to 75 degrees, such as 45 degrees to 65 degrees. 3D printingsome types of threaded bone implants in a head-to-tip direction may thusproduce threads that do not have the desired configuration after theprinting process.

One option to manufacture threaded bone implants with threads that aredisposed at certain angles is to print the threaded implants from thetip end (distal end) up to the head end (proximal end), the orientationof which is generally shown in FIG. 12A. Printing in this orientationmay, depending on the thread angles, produce threads at angles that arebeneficially less likely to droop or sag during the printing process. Toprint some threaded bone implants, it may be important to have a sturdybase upon which to print the implant upward to maintain a vertical longaxis throughout the printing process. FIG. 12A illustrates an exemplarydistal portion of 3D printed threaded implant 1200, including a printedsacrificial tip 1290 with a flattened base 1291, which is removed (e.g.,machining away) after the printing process to create the finished andoptionally sharpened distal tip configuration shown in FIG. 12B. In thisexample, the sacrificial tip 1290 includes a flattened base 1291 thatprovides a sturdy base upon which the implant may be printed up towardsthe head or proximal region. Printing in this orientation with anoptional sacrificial sturdy base may allow for 3D printing some threadedimplants that would be challenging to print if attempts were made toprint from the proximal head upward to a distal tip end.

One aspect of the disclosure is a method of a method of 3D printing athreaded bone implant (such as any of the threaded implants herein). Themethod may include printing a threaded bone implant from a distal end toa proximal end. The method may include printing an inner shank, printingat least one helical thread extending along at least a portion of thethreaded bone implant and extending from the inner shank. The method mayalso include printing a porous network of interconnected struts aboutthe inner shank, about a long axis of the elongate bone implant body,and between at least a section of the at least one helical thread, wherethe porous network of interconnected struts has an outer dimension lessthan a major diameter of the at least one helical thread. The method mayinclude printing the porous network of interconnected struts to besubstantially concentric about a long axis of the elongate body in atleast a portion of the porous network of interconnected struts. Themethod may include printing the porous network of interconnected strutsto have a general helical configuration extending along the elongatebody between the at least one helical thread and about the inner shank.The method may include printing the porous network of interconnectedstruts to have the same radially outermost dimension and concentricabout an elongate body long axis. The method may include printing strutends that are disposed within and coupled to fluted regions of theimplant. The method may include printing the porous network ofinterconnected struts to define a substantially smooth radially outersurface that approximate a cylindrical profile.

One aspect of the disclosure is a method of printing a threaded boneimplant. The method may include 3D printing a sacrificial distal tip andprinting a threaded bone implant above the sacrificial tip. The methodmay include removing the sacrificial tip (e.g., machining it away) andforming a distal end, optionally sharpened, on the distal end of thebone implant after removing the sacrificial tip.

It is understood that features of one or more embodiments herein may beintegrated with one or more other embodiments herein unless thedisclosure indicates to the contrary.

What is claimed is:
 1. A threaded bone stabilization implant adapted andsized for placement across a sacro-iliac (“SI”) joint, comprising: anelongate body having a distal end and a proximal end; the elongate bodyincluding a threaded distal region, a threaded central region disposedproximally of the distal region, and a proximal region disposedproximally of the central region, the elongate body further including aplurality of helical flutes, each of the plurality of helical fluteshaving formed therethrough a plurality of fenestrations extending into acentral lumen, the elongate body having a length, and the threadeddistal region, the threaded central region, and the proximal region eachhaving individual lengths such that when the implant is laterallyimplanted, the threaded distal region is positioned in a sacrum, thethreaded central region is positioned across an SI-joint, and theproximal region is positioned in an ilium, wherein each of the pluralityof helical flutes has formed therethrough a first set of one or morefenestrations extending into the central lumen in the threaded distalregion and a second set of one or more fenestrations extending into thecentral lumen in the threaded central region, at least one of the one ormore fenestrations in the distal region larger than at least one of theone or more fenestrations in the central region.
 2. The implant of claim1, wherein the threaded distal region is a multi-lead distal region, thethreaded central region is a single-lead central region, and theproximal region is a multi-lead proximal region.
 3. The implant of claim1, further comprising, an inner shank from which one or more threadsextend radially, and a porous network of interconnected struts disposedabout the inner shank.
 4. The implant of claim 1, wherein the pluralityof helical flutes consists of three helical flutes.
 5. The implant ofclaim 1, wherein each of the plurality of fenestrations has a radiallyinward taper.
 6. The implant of claim 1, wherein the length of thedistal region is from 10 mm to 22 mm, the length of the central regionis from 8 mm to 56 mm, and the length of the proximal region is from 6mm to 10 mm.
 7. A threaded bone stabilization implant adapted forplacement across a sacro-iliac (“SI”) joint, comprising: an elongatebody having a distal end and a proximal end; the elongate body includinga threaded multi-lead distal region, a threaded single-lead centralregion disposed proximally of the multi-lead distal region, and athreaded multi-lead proximal region disposed proximally of thesingle-lead central region; the body having a length, and the threadedmulti-lead distal region, the threaded single-lead central region, andthe threaded multi-lead proximal region each having individual lengthssuch that when the implant is laterally implanted across a SI joint, themulti-threaded distal region is positioned in a sacrum, the single-leadcentral region is positioned across the SI-joint, and the multi-leadproximal region is positioned in an ilium, wherein the elongate bodyfurther comprises a plurality of helical flutes formed therein, each ofthe plurality of helical flutes extending in the multi-lead distalregion, the single-lead central region, and optionally into themulti-lead proximal region, wherein each of the plurality of flutes hasa plurality of fenestrations aligned with the respective flute, theplurality of fenestrations spaced from each other along a length of theflute and extending into an elongate body central lumen, and whereineach of the plurality of fenestrations has a radially inward taper. 8.The implant of claim 7, wherein one or more fenestrations of theplurality of fenestration in the distal region has a greater angletapered configuration than one or more fenestrations of the plurality offenestrations in the central region.
 9. The implant of claim 7, whereinthe multi-lead distal region is a dual-lead region and the multi-leadproximal region is a dual-lead region.
 10. The implant of claim 7,wherein the multi-lead distal region, the single-lead central region,and the multi-lead proximal region each comprise an inner shank fromwhich the respective threads extend, the implant further comprising aporous network of interconnected struts disposed about the inner shank.11. The implant of claim 7, wherein the plurality of helical flutesconsists of three helical flutes.
 12. The implant of claim 7, wherein alength of the distal region is from 10 mm to 22 mm, a length of thecentral region is from 8 mm to 56 mm, and a length of the proximalregion is from 6 mm to 10 mm.